"""
num=27
remainder=[] #余数
letter=''
while num>0:
    remainder.append((num-1)%26)
    num = (num-1)//26

print(remainder)

for i in remainder[-1::-1]:
    letter+=chr(ord('A')+i)
print(letter)
"""
columnNumber=721
character=''
result=''
while(columnNumber>0):
    current=(columnNumber-1)%26
    columnNumber=(columnNumber-1)//26
    character=chr(ord('A')+current)
    result=character+result

print(result)